Chitosanase could cleave β-1,4-linkage of chitosan to produce chitooligosaccharides (COS) with diverse biological activities. However, there are many limitations on the use of free chitosanase in industrial production. Enzyme immobilization is generally considered a valuable strategy in industrial-scale applications. In this study, the chitosanase Csn-BAC from Bacillus sp. MD-5 was immobilized on Fe₃O₄-SiO₂ magnetic nanoparticles (MNPs) to enhance its properties, which could be recovered easily from reaction media using magnetic separation. The activities of Csn-BAC immobilized with MNPs (MNPs@Csn-BAC) were determined with temperature and pH, and the thermal- and pH-stabilities, respectively. The reusability of the MNPs@Csn-BAC was determined in repeated reaction cycles. Immobilization enhanced the thermal and pH stability of Csn-BAC compared with the free enzyme. After eight reaction cycles using MNPs@Csn-BAC, the residual enzyme activity was 72.15%. Finally, the amount of COS released by MNPs@Csn-BAC was 1.86 times higher than that of the free Csn-BAC in the catalytic performance experiment. The immobilized Csn-BAC exhibits broad application prospects in the production of COS.

壳聚糖酶可以裂解壳聚糖的β-1,4-键，产生具有多种生物活性的壳寡糖（COS）。然而，游离壳聚糖酶在工业生产中的使用存在诸多限制。酶固定化通常被认为是工业规模应用中的一种有价值的策略。在这项研究中，来自芽孢杆菌的壳聚糖酶 Csn-BAC 。MD-5 固定在 Fe ₃ O ₄ -SiO _2上磁性纳米粒子 (MNPs) 以增强其性能，可以使用磁分离从反应介质中轻松回收。分别用温度和 pH 值以及热稳定性和 pH 稳定性测定了用 MNP 固定的 Csn-BAC (MNPs@Csn-BAC) 的活性。在重复的反应循环中确定 MNPs@Csn-BAC 的可重复使用性。与游离酶相比，固定化增强了 Csn-BAC 的热稳定性和 pH 稳定性。使用 MNPs@Csn-BAC 进行 8 个反应循环后，残留酶活性为 72.15%。最后，在催化性能实验中，MNPs@Csn-BAC 释放的 COS 量是游离 Csn-BAC 的 1.86 倍。固定化Csn-BAC在COS生产中具有广阔的应用前景。